SOFsono JSOM case #4

Your team is participating in a remote operation in Afghanistan together with an Afghan team. As a result of an IED blast, 2 Afghanis are killed in action, and one of your team members is injured. On the initial assessment the U.S. operator has reassuring vitals:

Blood pressure (BP) 130/84 mmHg

Heart rate (HR) 85 BPM (beats per minute)

Respiratory rate (RR) 20

SpO2 99% on room air

and the following injuries:

multiple minor shrapnel wounds to the face and extremities

one large laceration of the right arm which requires tourniquet application

closed fracture of the right lower leg.

He is also complaining of cough and minimal dyspnea. As part of your initial assessment you perform an extended FAST (eFAST) exam, which is essentially negative.You have excluded free fluid in the pericardium, peritoneal and pleural cavities.There is no pneumothorax.

The estimated time of arrival (ETA) for the evacuation team is 18 hours.

At 6 hours after the injury your patient begins to deteriorate from respiratory standpoint. He has worsening cough, dyspnea and hemoptysis. His repeat vitals are:

BP 100/64

HR 120 BPM

RR 28

SpO2 92% on room air

Your repeat lung ultrasound excludes pneumothorax, but confirms your clinical suspicion of blast lung injury on the right. Due to rapid deterioration despite conservative measures, you decide to intubate your patient. Right after a successful endotracheal intubation you perform chest ultrasound to confirm bilateral lung ventilation. Your patient is stable at this point.

Based on the ultrasound findings, what action needs to be taken before the patient deteriorates?

Would capnography and/or clinical exam provide you with the same information prior to deterioration?

CLiNiCAL CONSiDERATiONS

Your patient has most likely sustained blast injury to his right lung, and he is showing symptoms & signs of rapid clinical deterioration. He has cough, dyspnea and hemoptysis. He is also becoming tachypneic and hypoxic. Given his imminent ventilatory failure you decide to intubate this patient. Immediately following the procedure your patient is stable. To make an educational point, let’s assume you are able to monitor end-tidal CO2. You notice normal PETCO2 (post-apneic end-tidal CO2) values and normal square capnography tracing. You think you heard equal bilateral breath sounds and no sounds on auscultation over the epigastrium.

Here is the thing! Even though your patient is stable, he seems to have equal bilateral breath sounds, and normal PETCO2 with a square waveform, you still haven’t determined the position of your tube. OK, it’s in the airway, but where? It’s not like you can call for a chest x-ray in the field!

Auscultation of breath sounds in unreliable to differentiate tracheal and bronchial intubation. Detection rates with a stethoscope hover around 65%. Furthermore, the use of standardized sizing for tube depth based on height and weight is prone to error, and assessment of PIP (peak inspiratory pressure) or MIP (mean inspiratory pressure) can also be misleading (1). To make it even worse, you cannot rely oncapnographyto rule out endobronchial intubation.

Identifying correct location of the tube in the trachea remains challenging, even in the hospital setting. Let alone in the field! Endobronchial intubation (right or left main stem tube) is the most common malposition encountered, and it happens in about 5 to 8% of all intubations. It can potentially lead to serious complications such as hypoxemia, atelectasis, hyperinflation, and barotrauma. It can also cause pulmonary infection if not diagnosed early (1). (Yikes in PFC!!!)

OPERATiONAL CONSiDERATiONS

This guy needs to be picked up – the sooner the better! You should primarily focus on preventing complications and good nursing care – you really don’t want that barotrauma or pulmonary infection from undiagnosed main stem tube! The smoother it runs, the bigger the chance your non-medical team members would be able to monitor the patient for you, while you catch a quick nap.

Now, letting non-medical folks babysit your patient on a vent, might sound like a heresy to some. However, if you are the only medically trained person out there, you also need some sleep. In ICU settings families at bedside are capable of alerting the staff when worrisome alarms go off. Why couldn’t you train your way smarter than an average bear SOF colleagues what trends and numbers to watch for, and when to wake you up?

SONOGRAPHiC MiSSiON SUPPORT

There is a multitude of ways in which ultrasound can aid airway management, especially in prolonged field care settings. This case is a perfect example! Ultrasound can help you prevent badness, way before trouble arrives.

Getting back to our case!

After the patient got intubated, tube position had to be checked. With color change of your colorimetric device or normal end-tidal CO2 tracing, and supposedly normal findings on clinical exam, you’d think you were good to go. But! Let’s just take the ultrasound probe and make sure we are ventilating both lungs, even though we thought we heard bilateral breath sounds.

How would we do it? That’s pretty simple! I am sure you know how to use M-mode to look for pneumothorax as part of your eFAST exam. The principle of lung sliding can be applied to confirm ventilation if your patient is intubated, the same way we look for pneumothorax. If you see sliding, the lung in question is being ventilated. Provided we excluded pneumo prior to intubation, lack of sliding means your tube ended up in the bronchus on the contralateral side.

Scanning our patient, on the right you can see the familiar seashore sign, which is consistent with normal lung sliding, and indicates lung ventilation. On the left the barcode sign which means there is no sliding movement. Given we’ve excluded pneumo twice in this case, barcode sign is consistent with lack of ventilation.

The conclusion? Our tube is in the right mainstem bronchus, and we need to pull it back before the patient develops any complications!

Now, in case you wondered where the balloon of your ETT was, there is a simple sono trick for that! Fill the cuff with saline, instead of air, to improve visualization, and place the linear probe transversely on the neck, any 2 cm above the suprasternal notch. Move the transducer cranially to verify the balloon is in correct midtracheal position. This method is much easier than looking for tracheal dilation as described in the reference article. Just don’t forget to replace that saline back with air!

So what other airway tricks can you pull off thanks to ultrasound?

Want to make your intubation safer and ensure that stomach isn’t full? Great – just do the eFAST LUQ scan. You’ll see fluid in the stomach if it’s there.

Having trouble finding that cricothyroid membrane? Unsure if you are in the right spot? Or maybe you want to mark it just in case, right before the RSI for endotracheal intubation? No problem – #SOFsono is the answer.

Don’t have videolaryngoscopy? No problem! You can use ultrasound for that!